Iñaki Baz Castillo writes:
I've never seen a PSTN gw properly handling a REFER, neither I think a PSTN gw should handle it (but a B2BUA/PBX) between the UA and the PSTN gw(s).
i don't see any problem if gw charges the call based on referred-by that proxy has verified. i think that even cisco ios gws with rather current software can do that.
Honestly I can imagine how a PSTN gw is supposed to assert the value of "Referred-By". Perhaps it just allows the REFER if it contains a Referred-By matching the From URI header?
gw does not assert the refer. it is the proxy that does that. gw simply generates a call to pstn and places the number in referred-by header to the charged party field of isdn or isup message. exactly the same as it does with diversion header, which has worked fine forever.
-- juha